JP5345171B2 - Endoscope - Google Patents

Description

The present invention relates to an endoscope that be irradiated with illumination light from a light source to the object of interest.

  The medical electronic endoscope has a built-in observation optical system and illumination optical system at the distal end, which is the distal end portion of the insertion portion inserted into the body, and illuminates the observed site with the illumination optical system, Image information of the illuminated site to be observed is extracted as a video signal by the observation optical system, and the image is displayed on a monitor or the like. The insertion portion accommodates a light guide in an internal space penetrating from the distal end portion to the proximal end portion. The light guide is, for example, a bundle of a large number of optical fibers. The illumination light is incident on one end (incident end) from an external light source device, the illumination light is guided to the tip, and the other end (exit) It is designed to inject from the end. Illumination light from the exit end is irradiated toward the observation site through the illumination optical system.

  In addition, in order to obtain preferable light distribution characteristics, the illumination light emitted from the light guide is made into a rod shape in which a clad having a refractive index lower than that of the core is formed around the core, which is a member of the central portion, like the optical fiber. An illumination optical system using this optical element is known (for example, see Patent Document 1). The illumination optical system of Patent Document 1 has a configuration in which two plano-convex lenses are arranged at an appropriate interval on the light exit side of the optical element, and is a light beam parallel to the optical axis of the illumination light emitted from the light guide. Is once converged in the illumination optical system, and then diverged to obtain a desired light distribution.

  In the electronic endoscope, when the temperature of the tip increases, the image pickup signal obtained from the image sensor increases in noise, which may affect image quality degradation and the subject. For this reason, measures have been taken to suppress the temperature rise at the tip, but in recent years, the number of pixels in the image sensor has increased, and heat generation at the tip has increased as power consumption has increased.

JP 2002-182126 A

  By the way, the illumination light guided to the tip through the light guide is passed through a heat ray cut filter or the like before the illumination light is incident on the light guide from the light source device so that the temperature of the tip is not increased. Yes. However, even when a part of the illumination light is blocked in the illumination optical system or the like, a loss of the light amount occurs, which becomes heat and raises the temperature of the tip.

  On the other hand, the illumination light emitted from the light guide includes many light rays that are spread and emitted in accordance with the numerical aperture of the light guide. Therefore, in the illumination optical system configured as in Patent Document 1, there is also a light beam that proceeds while being inclined with respect to the optical axis and is emitted from the peripheral portion of the exit surface of the optical element and travels substantially in parallel. For this reason, in the case where the interval ring is sandwiched between the optical element and the lens as in the prior art and the interval is defined, the optical element is emitted from the peripheral portion of the emission surface of the optical element and is substantially aligned with the optical axis. There is a problem in that light beams traveling in parallel are blocked by the spacing ring, resulting in a loss of light amount, which causes a decrease in illumination efficiency and a rise in temperature at the tip.

  The present invention has been made in view of the above problems, and an object thereof is to provide an endoscope illumination optical system and an endoscope that can reduce the loss of the amount of illumination light.

In order to achieve the above object, an endoscope of the present invention has an illumination optical device that irradiates an observation site with illumination light from a light source device transmitted to a distal end portion of an insertion portion via a light guide. The illumination optical device has a lens mounting hole formed in the tip body constituting the tip, a lens barrel fitted in the lens mounting hole, an incident surface facing the light guide, and a light reflecting function. An optical element having an outer peripheral portion having a convex surface and a convex exit surface, and having an outer diameter larger than that of the optical element and housed in a lens mounting hole, and maintaining an optical distance at a predetermined interval. A first lens disposed in front of the element, and a space surrounded by the lens barrel or the lens mounting hole is formed between the optical element and the first lens, and the diameter of the space is equal to or greater than the outer diameter of the optical element. It is what.

The illumination optical device is provided with a light guide mounting hole formed in the tip body for storing the light guide. The light guide mounting hole is continuous with the lens mounting hole, and its inner diameter is larger than the outer diameter of the lens barrel. Is preferably small. Further, it is preferable that the light guide has an outer diameter substantially the same as that of the optical element. Furthermore, it is preferable that the incident surface of the optical element is a flat surface and is substantially flush with the rear end of the lens barrel.

The illumination optical device preferably includes a second lens disposed in front of the first lens in the lens mounting hole and having the same outer diameter as the first lens. The second lens is preferably a convex surface whose incident surface protrudes toward the first lens, has a flat exit surface, and is flush with the distal end surface of the distal end body. It is preferable to provide an interval ring that is disposed between the first lens and the second lens and maintains the interval between the first lens and the second lens.

The length of the lens barrel is shorter than the lens mounting hole, the front end is located inside the lens mounting hole, the first lens is in contact with the front end, the first lens, the spacer ring, and the second lens. Is preferably fitted in the lens mounting hole.

The lens barrel has the same length as the lens mounting hole, and has a small diameter portion with a small inner diameter, a large diameter portion with a large inner diameter, and a step portion formed between the small diameter portion and the large diameter portion. Preferably, the optical element is fitted to the small diameter portion, the first lens is in contact with the stepped portion, and the first lens, the spacing ring, and the second lens are fitted to the large diameter portion.

Moreover, it is preferable that the peripheral surface of the optical element is fixed to the lens barrel.

The lens barrel is preferably fixed in the lens mounting hole with a screw.

In addition, the endoscope of the present invention includes an illumination optical device that irradiates the observation site with illumination light from the light source device transmitted to the distal end portion of the insertion portion via the light guide. An apparatus is a lens having a small-diameter portion having a small inner diameter, a large-diameter portion having a large inner diameter, and a step portion formed between the small-diameter portion and the large-diameter portion. An optical element having a mounting hole, an incident surface facing the light guide, an outer peripheral part having a light reflection function, and a convex emission surface, and an outer diameter larger than that of the optical element. A lens mounting hole between the optical element and the first lens, which is large and fitted to the large-diameter part in a state where it is in contact with the stepped part, and is disposed in front of the optical element with a predetermined interval. An enclosed space is formed, and the diameter of this space is greater than or equal to the outer diameter of the optical element. .

A second lens fitted in the large diameter portion and disposed in front of the first lens, and disposed between the first lens and the second lens to maintain a distance between the first lens and the second lens. It is preferable to provide a ring.

As the optical element , a rod lens having a core and a clad formed around the core and having a refractive index lower than that of the core can be used.

  In the present invention, when the lens is arranged at a predetermined interval apart from the optical element having the light reflecting function of the outer peripheral portion and the function of the convex lens on the exit side, the outer diameter of the lens is larger than the optical element, Since the inner diameter of the space between the optical element and the lens is set to be equal to or larger than the outer diameter of the optical element, the light beam that is emitted from the peripheral edge of the emission side surface of the optical element and travels substantially parallel to the optical axis is not blocked. Since the light is incident on the lens, it is possible to reduce the light amount loss of the illumination light inside the illumination optical system. In addition, since heat generation due to light loss can be suppressed, temperature rise at the tip can be suppressed.

It is a schematic diagram of an endoscope system. It is a disassembled perspective view which shows the illumination optical system accommodated in the front-end | tip part main body. It is sectional drawing which shows the illumination optical system assembled | attached in the lens mounting hole. It is sectional drawing which shows the example which attaches an optical element and a 1st, 2nd lens to a lens-barrel. It is sectional drawing which shows the example which assembles | attaches an optical element and a 1st, 2nd lens directly to a lens mounting hole. It is sectional drawing which shows the example which screwed the lens-barrel.

  An endoscope system is shown in FIG. The endoscope system 10 includes an electronic endoscope 11, a processor device 12, and a light source device 13. The electronic endoscope 11 is connected to a flexible insertion portion 16 to be inserted into a subject and a proximal end portion of the insertion portion 16, and is used for grasping the electronic endoscope 11 and operating the insertion portion 16. And a universal cord 18 that connects the operation unit 17 to the processor device 12 and the light source device 13, respectively. An imaging element, an objective optical system 19, and a pair of illumination optical systems 20 (both see FIG. 2) are built in the distal end portion 16a that is the distal end portion of the insertion portion 16. A bendable bending portion 16b is connected to the rear end of the tip portion 16a.

  The operation unit 17 is provided with an angle knob 22, an operation button 23, and a forceps inlet 24. The angle knob 22 is rotated when adjusting the bending direction and the bending amount of the insertion portion 16. The operation buttons 23 are used for various operations such as air / water supply and suction. The forceps inlet 24 communicates with a forceps channel inserted into the insertion portion 16. An air / water channel, a signal cable and the like are passed through the universal cord 18.

  The processor device 12 is electrically connected to the electronic endoscope 11 and the light source device 13 and comprehensively controls the operation of the electronic endoscope system 10. The processor device 12 controls the driving of the image sensor at the distal end portion 16 a via the universal cord 18 and a signal cable inserted into the insertion portion 16. Further, the processor device 12 acquires an imaging signal output from the imaging device via a signal cable, performs various image processing, and displays the image on the monitor 14 as an observation image.

  The light source device 13 has a built-in illumination light source. The illumination light from the light source device 13 is guided to the illumination optical system 20 through the light guide 27 (see FIG. 3), and is irradiated from the illumination optical system 20 to the observation site. The light guide 27 is formed by bundling a large number of optical fibers (fiber strands) in a cylindrical shape, for example, and is passed through the inside of the universal cord 18 and the insertion portion 16, and the end on the emission side is the tip. It has reached part 16a. The light guide 27 receives illumination light from a light source on an end surface (hereinafter referred to as an incident end surface) of an incident side end inserted into the light source device 13 and guides the illumination light to the tip end portion 16a. It injects from the end surface (henceforth an injection | emission end surface) 27a (refer FIG. 3) of a part.

  As shown in FIG. 2, the distal end portion 16 a includes a columnar distal end portion main body 31, the above-described imaging device, objective optical system 19, and a pair of illumination optical systems 20 incorporated therein. The tip end body 31 is formed of a hard resin or a metal material. The distal end surface 31a of the distal end main body 31 is provided with an observation window 33, a pair of illumination windows 34, an air / water supply nozzle 35, and a forceps outlet 36 serving as an outlet of a forceps channel.

  The observation window 33 is for capturing an image of a region to be observed. The objective optical system 19 is incorporated in the back of the observation window 33, and a part thereof is exposed. An imaging element is arranged at the ridge of the objective optical system 19, and an image of the observation site is taken through the objective optical system 19 by this imaging element.

  The illumination window 34 is for illuminating the site to be observed, and the illumination optical system 20 is incorporated in the interior thereof. The illumination optical system 20 distributes the illumination light emitted from the light guide 27 so that the imaging range is illuminated uniformly, for example, so as to be suitable for imaging. The pair of illumination windows 34 are provided on both sides of the observation window 33, but the number and arrangement of the illumination windows 34 can be changed as appropriate.

  Each illumination optical system 20 is inserted and assembled in a lens mounting hole 38 formed in the distal end main body 31. The lens mounting hole 38 is formed to extend rearward from the front end surface 31a along the optical axis PL of the illumination optical system 20, and an opening at the front end surface 31a serves as an illumination window 34. Further, as shown in FIG. 3, a light guide mounting hole 39 into which the light guide 27 is fitted is formed in the distal end portion body 31 at the back of the lens mounting hole 38. The lens mounting hole 38 and the light guide mounting hole 39 are both holes having a circular cross section and are formed coaxially.

  The illumination optical system 20 includes an optical element 40, a first lens 41, a second lens 42, a lens barrel 43, and a spacing ring 44. The illumination optical system 20 is inserted into the lens mounting hole 38 in the order of the lens barrel 43 to which the optical element 41 is fixed, the first lens 41, the spacing ring 44, and the second lens 42.

  As shown in FIG. 3, the optical element 40 is a substantially cylindrical rod lens in which a clad 46b having a refractive index lower than that of the core 46a is formed around a core 46a that is a central member. The optical element 40 has a light incident side (light guide side) surface 40a as a flat surface, and a light emission side (illumination window side) surface 40b as a convex surface, and has a function of a convex lens. .

  In addition, the optical element 40 reflects light incident from the surface 40a and guides it to the surface 40b side by the difference in refractive index between the core 46a and the clad 46b, like the optical fiber. The outer peripheral portion has a light reflecting function. The optical element 40 may be configured by combining a plurality of members so as to have an equivalent function. For example, a reflection surface may be formed on the outer peripheral surface of the plano-convex lens.

  The lens barrel 43 holds the optical element 40 therein and also functions as an interval ring that separates the first lens 41 from the optical element 40 at a predetermined interval as will be described later. The inner diameter of the lens barrel 43 is the same as the outer diameter of the optical element 40, and the outer diameter is the same as the inner diameter of the lens mounting hole 38. The optical element 40 is fixed in the lens barrel 43 so as not to cause a step between the surface 40a and the end of the lens barrel 43 on the ride guide side, and is inserted into the lens mounting hole 38 together with the lens barrel 43. Inserted. The lens barrel 43 is shorter than the lens mounting hole 38.

  The lens barrel 43 is provided with a hole 43a (see FIG. 2) on its peripheral surface. The optical element 40 is fixed to the lens barrel 43 when, for example, a thermosetting resin is dropped into the hole 43a in a state of being inserted into the lens barrel 43 and is cured.

  The light guide mounting hole 39 has an inner diameter smaller than the lens mounting hole 38 by substantially the thickness of the lens barrel 43 (for example, about 0.1 mm). By forming the mounting holes 38 and 39 having different diameters in a coaxial manner in this way, the abutment surface 48 surrounds the light guide mounting hole 39 at the boundary between the lens mounting hole 38 and the light guide mounting hole 39. Is formed. The edge of the lens barrel 43 on the light guide side abuts and is brought into contact with the abutting surface 48, whereby the lens barrel 43 and the optical element 40 being held are positioned. The lens barrel 43 is fixed to the lens mounting hole 38 by, for example, curing a thermosetting resin applied between the outer peripheral surface thereof and the inner surface of the lens mounting hole 38.

  The outer diameter of the ride guide 27 is substantially the same as the inner diameter of the light guide mounting hole 39 and is substantially the same as the outer diameter of the optical element 40. The ride guide 27 is fixed by being fitted into the light guide mounting hole 39 with the emission end surface 27a in close contact with the surface 40a of the optical element 40. Thus, all of the illumination light emitted from the emission end face 27a is incident on the surface 40a of the optical element 40 while preventing the outer diameter of the optical element 40 from becoming unnecessarily large.

  In the optical element 40, a region where the effective light is incident on the surface 40 a is a portion of the core 46 a, and the diameter of the core 46 a is slightly smaller than the outer diameter of the optical element 40. For this reason, the outer diameter of the ride guide 27 may be made slightly smaller than the outer diameter of the optical element 40 in accordance with the diameter of the core 46a, and in this example as well.

  The first lens 41 is a convex lens having a light incident side surface 41a and an emission side surface 41b, both of which are biconvex. The first lens 41 has the same outer diameter as the inner diameter of the lens mounting hole 38, and is larger than the outer diameter of the optical element 40. The first lens 41 is inserted in the lens mounting hole 38 to a position where it abuts the edge on the exit side of the lens barrel 43 with the outer peripheral surface supported by the lens mounting hole 38. By contact with the lens barrel 43, the first lens 41 is positioned at a position separated from the optical element 40 by a predetermined interval. The length of the lens barrel 43 is determined based on the length of the optical element 40, the design interval between the optical element 40 and the first lens 41, and the like.

  Further, since the inner diameter of the lens barrel 43 is the same as the outer diameter of the optical element 40, the inner diameter of the space between the optical element 40 and the first lens 41 is the same as the outer diameter of the optical element 40. Yes. Thereby, the illumination light emitted from the peripheral portion of the surface 40b of the optical element 40 can be incident on the first lens 41 without being blocked. The inner diameter of the lens barrel portion between the optical element 40 and the first lens may be larger than the outer diameter of the optical element 40. From the viewpoint of reducing the diameter of the insertion portion 16, this example It is better to make it the same.

  The spacing ring 44 has a ring shape, and the inner diameter and the outer diameter thereof are the same as those of the lens barrel 43, for example. The spacing ring 44 defines the spacing between the first lens 41 and the second lens 42, and is disposed between the first lens 41 and the second lens 42.

  The second lens 42 is a plano-convex convex lens in which the light incident side surface 42 a is convex and the emission side surface 42 b is planar, and the surface 42 b is exposed from the illumination window 34. The second lens 42 has an outer diameter that is the same as the inner diameter of the lens mounting hole 38, and is inserted into the lens mounting hole 38 with its outer peripheral surface supported by the lens mounting hole 38.

  The second lens 42 is fixed to the lens mounting hole 38 with the first lens 41 and the spacing ring 44 sandwiched between the second lens 42 and the lens barrel 43. The second lens 42 is fixed, for example, by curing a thermosetting resin applied between the outer peripheral surface thereof and the inner surface of the lens mounting hole 38. By fixing the lens barrel 43 and the second lens in the lens mounting hole 38 in this way, the first lens 41 and the spacing ring 44 are fixed while being sandwiched between the lens barrel and the second lens.

  In order to apply the thermosetting resin to the outer peripheral surface of the lens barrel 43 and the second lens 42 and the inner surface of the lens mounting hole 38, for example, the lens barrel 43 and the second lens 42 are slightly smaller than the inner diameter of the lens mounting hole 38. It is made small (for example, about 10 μm). It should be noted that a groove into which the thermosetting resin enters may be formed in the lens barrel 43, the outer peripheral surface of the second lens 42, or the inner surface of the lens mounting hole 38.

  Although the outer diameters of the first lens 41 and the second lens 42 are larger than the outer diameters of the optical element 40 and the lens barrel 43, the first lens 41, The outer peripheral surface of the second lens 42 is directly supported. For this reason, even if the outer diameters of the lenses 41 and 42 are increased, it is not necessary to increase the diameter of the distal end portion 16a.

  According to the above configuration, when the light source of the light source device 13 is turned on, the illumination light from the light source is incident on the incident end face of the light guide 27. Thereby, illumination light is guide | induced to the front-end | tip part 16a through the light guide 27, and is inject | emitted from the injection | emission end surface 27a.

  Illumination light emitted from the emission end face 27 a enters the optical element 40. The illumination light emitted from the exit end face 27a includes light rays that travel in various directions corresponding to the numerical aperture of the light guide 27, and light rays parallel to the optical axis PL are included in the illumination optical system 20. Once converged in the light, it is emitted and irradiated to the site to be observed.

  On the other hand, as indicated by a broken line in FIG. 3, there is also a light ray that proceeds while being inclined with respect to the optical axis and is emitted from the peripheral edge of the surface 40a of the optical element 40 and travels substantially parallel to the optical axis PL. Since the inner diameter of the space between the optical element 40 and the first lens 41 is the same as the outer diameter of the optical element 40, and there is no shield in the region where the optical element 40 is projected in the optical axis direction, the surface 40a A light beam emitted from the peripheral edge and traveling substantially parallel to the optical axis PL is incident on the first lens 41 without being blocked, and is further irradiated to the observation site via the second lens 42.

  As described above, since light that travels substantially parallel to the optical axis PL after being emitted from the peripheral edge of the surface 40a can be used for illumination without being blocked, illumination light with a large amount of light is irradiated onto the site to be observed. Moreover, since the light quantity loss of the illumination light inside the illumination optical system 20 is reduced, heat generation due to the light quantity loss is suppressed, and as a result, the temperature rise of the tip portion 16a is suppressed.

  FIG. 4 shows an example in which the first and second lenses are assembled to the lens barrel, similarly to the optical element. In addition, except being demonstrated below, it is the same as that of the said embodiment, The same code | symbol is attached | subjected to the same structural member, and the detailed description is abbreviate | omitted.

  The optical element 40, the first lens 41, and the second lens 42 are fixed to the lens barrel 53, and the lens barrel 53 is fitted into the lens mounting hole 54 and fixed. In the lens barrel 53, the inner diameter of the portion that holds the optical element 40 and the portion between the optical element 40 and the first lens 41 is the same as the inner diameter of the optical element 40, and is emitted from the peripheral portion of the surface 40a. Thus, the light beam traveling substantially parallel to the optical axis PL is incident on the first lens 41 without being blocked. Further, the inner diameter of the portion that holds the second lens 42 from the first lens 41 is the same as the outer diameter of the lenses 41 and 42.

  According to this example, the lens barrel 53 has an outer diameter that is larger than that of the above-described embodiment at a portion that holds the first and second lenses 41 and 42, and requires a larger amount of space at the tip. However, there is an advantage that the illumination optical system 20 can be unitized and, for example, replacement is easy.

  FIG. 5 shows an example in which the optical element is directly held on the tip body, similarly to the first and second lenses. In addition, except being demonstrated below, it is the same as that of 1st embodiment, the same code | symbol is attached | subjected to the same structural member, and the detailed description is abbreviate | omitted.

  In this example, the optical element 40 is directly held in the lens mounting hole 55 and fixed in the same manner as the first and second lenses 41 and 42 without using a lens barrel. For this reason, the inner diameter of the lens mounting hole 55 is the same as the outer diameter of the optical element 40 in the portion holding the optical element 40. The inner diameter of the portion between the optical element 40 and the first lens 41 is also the same as the inner diameter of the optical element 40, and the light beam that is emitted from the peripheral edge of the surface 40a and travels substantially parallel to the optical axis PL is blocked. In this case, the light enters the first lens 42.

  Further, the lens mounting hole 55 is configured such that the first lens 41 comes into contact with a step 55 a formed at a boundary between a portion having the same inner diameter as the outer diameter of the optical element 40 and a portion having the same inner diameter as the outer diameter of the first lens 41. Thus, the distance between the optical element 40 and the first lens 41 is defined as a predetermined distance.

  According to this example, in order to position the optical element 40 in the lens mounting hole 55, the inner diameter of the ride guide mounting hole 39 needs to be smaller than the outer diameter of the optical element 40. Since the outer diameter of the ride guide 27 is limited by the inner diameter of the ride guide mounting hole 39, it must be smaller than the outer diameter of the optical element 40, and the size of the optical element 40 can be fully utilized. Although not provided, the lens barrel can be omitted, which is advantageous in reducing the number of parts and saving space.

  In the above embodiments, the method of fixing the lens barrel to the lens mounting hole and the method of fixing the optical element or each lens to the lens barrel are not limited to those described above. An ultraviolet curable resin may be used instead of the thermosetting resin, or an adhesive may be used. Further, as shown in FIG. 6, the lens barrel 43 may be fixed to the distal end body 31 with a screw 58.

  In the above embodiment, an example in which two lenses are used as the optical system on the exit side of the optical element has been described. However, the configuration is not limited to this, and for example, a single lens may be used. It is good also as the above lens. In the case of an optical element and a single lens, the lens may be aspherical so that preferable light distribution characteristics can be obtained. Further, as shown in Patent Document 1, the first lens may be a plano-convex convex lens in which the light incident side is a flat surface and the emission side is a convex surface.

DESCRIPTION OF SYMBOLS 11 Electronic endoscope 20 Illumination optical system 27 Light guide 38 Lens mounting hole 39 Light guide mounting hole 40 Optical element 41 1st lens 42 2nd lens 43 Lens tube 44 Space ring

Claims (14)

In an endoscope having an illumination optical device that irradiates the observation site from the distal end portion with illumination light from the light source device transmitted to the distal end portion of the insertion portion via the light guide
The illumination optical device comprises:
A lens mounting hole formed in a tip body constituting the tip,
A lens barrel fitted in the lens mounting hole;
An optical element that has an incident surface facing the light guide, an outer peripheral portion having a light reflection function, and a convex emission surface, and is held in the lens barrel;
A first lens having a larger outer diameter than the optical element, housed in the lens mounting hole, and disposed in front of the optical element at a predetermined interval;
The space surrounded by the lens barrel or said lens mounting hole between the optical element and the first lens is formed, an endoscope, wherein the diameter of this space is equal to or greater than the outer diameter of the optical element . The illumination optical device includes a light guide mounting hole formed in the tip body to store the light guide,
The endoscope according to claim 1, wherein the light guide mounting hole is continuous with the lens mounting hole and has an inner diameter smaller than an outer diameter of the lens barrel . The endoscope according to claim 2 , wherein the light guide has substantially the same outer diameter as the optical element . 4. The endoscope according to claim 2 , wherein the incident surface of the optical element is a flat surface and is substantially flush with a rear end of the barrel . The illumination optical apparatus, the lens is disposed in front of the first lens mounting hole, any one of claims 1 to 4 wherein the first lens and the outer diameter, characterized in that it comprises the same second lens 1 The endoscope according to item . 2. The second lens according to claim 1, wherein an incident surface of the second lens is a convex surface protruding toward the first lens, an exit surface is flat, and is flush with a distal end surface of the distal end body. 5. The endoscope according to 5 . The internal vision according to claim 5 or 6 , further comprising a spacing ring disposed between the first lens and the second lens to maintain a spacing between the first lens and the second lens. mirror. The lens barrel is shorter in length than the lens mounting hole, the front end is located inside the lens mounting hole, and the first lens is in contact with the front end,
The endoscope according to claim 7 , wherein the first lens, the spacer ring, and the second lens are fitted in the lens mounting hole . The lens barrel has the same length as the lens mounting hole, a small diameter portion having a small inner diameter, a large diameter portion having a large inner diameter, and a step portion formed between the small diameter portion and the large diameter portion. The optical element is fitted into the small diameter portion, the first lens is in contact with the stepped portion, and the first lens, the spacing ring, and the second lens are in the large diameter portion. The endoscope according to claim 7 , wherein the endoscope is fitted . The endoscope according to any one of claims 1 to 9, wherein a peripheral surface of the optical element is fixed to the lens barrel . The endoscope according to any one of claims 1 to 10, wherein the lens barrel is fixed in the lens mounting hole by a screw. In an endoscope having an illumination optical device that irradiates the observation site from the distal end portion with illumination light from the light source device transmitted to the distal end portion of the insertion portion via the light guide,
The illumination optical device comprises:
A lens having a small-diameter portion with a small inner diameter, a large-diameter portion with a large inner diameter, and a step portion formed between the small-diameter portion and the large-diameter portion. Mounting holes;
An optical element having an incident surface facing the light guide, an outer peripheral portion having a light reflecting function, and a convex exit surface, and fitted into the small diameter portion;
A first lens having a larger outer diameter than the optical element, fitted to the large diameter portion in a state of being contacted with the stepped portion, and disposed in front of the optical element with a predetermined interval;
An endoscope characterized in that a space surrounded by the lens mounting hole is formed between the optical element and the first lens, and the diameter of the space is equal to or larger than the outer diameter of the optical element. A second lens fitted to the large diameter portion and disposed in front of the first lens;
The endoscope according to claim 12, further comprising a spacing ring disposed between the first lens and the second lens for maintaining a spacing between the first lens and the second lens. . The endoscopic device according to any one of claims 1 to 13, wherein the optical element is a rod lens having a core and a clad formed around the core and having a refractive index lower than that of the core. mirror.

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